feat: 引入 Rust executor/gateway sidecar 及 Python 侧双后端适配

- 新增 Rust workspace crates: aether-contracts, aether-executor, aether-gateway
- aether-executor: 支持 Unix Socket/TCP 双传输模式，处理同步/流式上游请求
- aether-gateway: 作为本地主入口代理，集成 /api/internal/gateway/resolve 认证预解析
- Python 侧新增 ExecutionPlan 契约和 RustExecutorClient，各 handler 支持
  executor_backend=rust 时将可序列化请求转发给 Rust executor 执行
- 重构 dev.sh 支持 executor/gateway 进程编排与生命周期管理
- 新增 internal gateway 路由，提供 resolve/passthrough 端点
- handler 层(chat/cli/video/endpoint_checker 等)全面适配 Rust executor 回退逻辑
- pipeline 层支持 trusted auth context 跳过重复认证
- 新增 Rust CI workflow 及对应测试用例

tests/api/public/test_system_catalog_rust.py

@@ -0,0 +1,142 @@
+from __future__ import annotations
+
+from types import SimpleNamespace
+from unittest.mock import AsyncMock, MagicMock
+
+import httpx
+import pytest
+
+
+def _build_provider_fixture() -> SimpleNamespace:
+    endpoint = SimpleNamespace(
+        id="endpoint_1",
+        base_url="https://upstream.test",
+        api_format="openai:chat",
+        is_active=True,
+    )
+    key = SimpleNamespace(
+        id="key_1",
+        is_active=True,
+        api_formats=None,
+    )
+    return SimpleNamespace(
+        id="provider_1",
+        name="openai",
+        endpoints=[endpoint],
+        api_keys=[key],
+    )
+
+
+@pytest.mark.asyncio
+async def test_test_connection_prefers_rust_executor(
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    from src.api.public import system_catalog as mod
+
+    provider = _build_provider_fixture()
+
+    monkeypatch.setattr(mod, "_select_provider", lambda _db, _provider_name: provider)
+    monkeypatch.setattr(mod, "build_test_request_body", lambda *_args, **_kwargs: {"model": "gpt-test"})
+    monkeypatch.setattr(mod, "get_provider_auth", AsyncMock(return_value=None))
+
+    class _DummyBuilder:
+        def build(self, *_args: object, **_kwargs: object) -> tuple[dict[str, str], dict[str, str]]:
+            return {"model": "gpt-test"}, {"authorization": "Bearer test"}
+
+    monkeypatch.setattr(mod, "PassthroughRequestBuilder", lambda: _DummyBuilder())
+    monkeypatch.setattr(
+        mod,
+        "build_provider_url",
+        lambda *_args, **_kwargs: "https://upstream.test/v1/chat/completions",
+    )
+
+    proxy_snapshot = object()
+    monkeypatch.setattr(
+        mod,
+        "_build_test_connection_transport_context",
+        AsyncMock(return_value=({"enabled": True}, {"node_id": "node-1", "tunnel": True}, proxy_snapshot)),
+    )
+
+    rust_response = httpx.Response(
+        200,
+        request=httpx.Request("POST", "https://upstream.test/v1/chat/completions"),
+        json={"id": "resp_rust"},
+    )
+    rust_call = AsyncMock(return_value=rust_response)
+    monkeypatch.setattr(mod, "_try_rust_test_connection_response", rust_call)
+
+    get_upstream_client = AsyncMock(side_effect=AssertionError("python upstream client should not be used"))
+    monkeypatch.setattr(mod.HTTPClientPool, "get_upstream_client", get_upstream_client)
+
+    result = await mod.test_connection(
+        request=SimpleNamespace(query_params={}),
+        db=MagicMock(),
+        provider=None,
+        model="gpt-test",
+        api_format=None,
+    )
+
+    assert result["status"] == "success"
+    assert result["response_id"] == "resp_rust"
+    rust_call.assert_awaited_once()
+    get_upstream_client.assert_not_awaited()
+
+
+@pytest.mark.asyncio
+async def test_test_connection_fallback_uses_transport_aware_client(
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    from src.api.public import system_catalog as mod
+
+    provider = _build_provider_fixture()
+
+    monkeypatch.setattr(mod, "_select_provider", lambda _db, _provider_name: provider)
+    monkeypatch.setattr(mod, "build_test_request_body", lambda *_args, **_kwargs: {"model": "gpt-test"})
+    monkeypatch.setattr(mod, "get_provider_auth", AsyncMock(return_value=None))
+
+    class _DummyBuilder:
+        def build(self, *_args: object, **_kwargs: object) -> tuple[dict[str, str], dict[str, str]]:
+            return {"model": "gpt-test"}, {"authorization": "Bearer test"}
+
+    monkeypatch.setattr(mod, "PassthroughRequestBuilder", lambda: _DummyBuilder())
+    monkeypatch.setattr(
+        mod,
+        "build_provider_url",
+        lambda *_args, **_kwargs: "https://upstream.test/v1/chat/completions",
+    )
+
+    proxy_config = {"enabled": True, "url": "http://proxy.test:8080"}
+    delegate_cfg = {"node_id": "node-1", "tunnel": True}
+    monkeypatch.setattr(
+        mod,
+        "_build_test_connection_transport_context",
+        AsyncMock(return_value=(proxy_config, delegate_cfg, None)),
+    )
+    monkeypatch.setattr(mod, "_try_rust_test_connection_response", AsyncMock(return_value=None))
+
+    upstream_response = httpx.Response(
+        200,
+        request=httpx.Request("POST", "https://upstream.test/v1/chat/completions"),
+        json={"id": "resp_python"},
+    )
+    upstream_client = MagicMock()
+    upstream_client.post = AsyncMock(return_value=upstream_response)
+    get_upstream_client = AsyncMock(return_value=upstream_client)
+    monkeypatch.setattr(mod.HTTPClientPool, "get_upstream_client", get_upstream_client)
+
+    result = await mod.test_connection(
+        request=SimpleNamespace(query_params={}),
+        db=MagicMock(),
+        provider=None,
+        model="gpt-test",
+        api_format=None,
+    )
+
+    assert result["status"] == "success"
+    assert result["response_id"] == "resp_python"
+    get_upstream_client.assert_awaited_once_with(delegate_cfg, proxy_config=proxy_config)
+    upstream_client.post.assert_awaited_once_with(
+        "https://upstream.test/v1/chat/completions",
+        json={"model": "gpt-test"},
+        headers={"authorization": "Bearer test"},
+    )